SC TO-T/A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Amendment No. 22

to

SCHEDULE TO

(Rule 14d-100)

Tender Offer Statement under Section 14(d)(1) or 13(e)(1) of

the Securities Exchange Act of 1934

VENTANA MEDICAL SYSTEMS, INC.

(Name of Subject Company)

ROCKET ACQUISITION CORPORATION

ROCHE HOLDING LTD

(Names of Filing Persons — Offeror)

Common Stock, Par Value $0.001 Per Share

(including the associated preferred stock purchase rights)

(Title of Class of Securities)

92276H106

(Cusip Number of Class of Securities)

Beat Kraehenmann

Roche Holding Ltd

Grenzacherstrasse 124

CH-4070 Basel

Switzerland

Telephone: +41-61-688-1111

(Name, Address and Telephone Number of Person Authorized to ReceiveNotices

and Communications on Behalf of Filing Persons)

Copies to:

Christopher Mayer

Davis Polk & Wardwell

450 Lexington Avenue

New York, New York 10017

Telephone: (212) 450-4000

CALCULATION OF FILING FEE

Transaction Valuation*	Amount of Filing Fee**
$3,444,141,596	$135,354.76

* Estimated for purposes of calculating the filing fee only. This amount assumes the purchase of all 34,844,346 shares of common stock of Ventana Medical Systems, Inc. outstanding as of January 20, 2008, all options outstanding as of January 20, 2008 with respect to 4,895,184 shares of common stock of Ventana, and all performance units outstanding as of January 20, 2008 with respect to 43,104 shares of common stock of Ventana.

** The amount of the filing fee is calculated in accordance with Rule 0-11 of the Securities Exchange Act of 1934, as amended, by multiplying the transaction valuation by 0.00003930.

R Check box if any part of the fee is offset as provided by Rule 0-11(a)(2) and identify the filing with which the offsetting fee was previously paid. Identify the previous filing by registration statement number, or the Form or Schedule and the date of its filing.

Amount Previously Paid:	$43,902.45	Filing Party:	Roche Holding Ltd
Form or Registration No.:	SC TO-T/A	Date Filed:	January 22, 2008

Amount Previously Paid:	$91,452.31	Filing Party:	Roche Holding Ltd
Form or Registration No.:	SC TO-T	Date Filed:	June 27, 2007

£ Check the box if the filing relates solely to preliminary communications made before the commencement of a tender offer.

Check the appropriate boxes below to designate any transactions to which the statement relates:

R third-party tender offer subject to Rule 14d-1.

£ issuer tender offer subject to Rule 13e-4.

£ going-private transaction subject to Rule 13e-3.

£ amendment to Schedule 13D under Rule 13d-2.

Check the following box if the filing is a final amendment reporting the results of the tender offer.  R

Items 1 through 9.

This Amendment No. 22 to Tender Offer Statement on Schedule TO (the “Schedule TO”) amends and supplements the statement originally filed on June 27, 2007 by Roche Holding Ltd, a joint stock company organized under the laws of Switzerland (“Parent”), and Rocket Acquisition Corporation (the “Purchaser”), a Delaware corporation and an indirect wholly owned subsidiary of Parent. This Schedule TO relates to the offer by the Purchaser to purchase all outstanding shares of common stock, par value $0.001 per share (together with the associated preferred stock purchase rights, the “Shares”), of Ventana Medical Systems, Inc., a Delaware corporation (the “Company”), at $89.50 per Share, net to the seller in cash, without interest and less applicable withholding taxes, upon the terms and subject to the conditions set forth in the Amended and Restated Offer to Purchase, dated January 25, 2008 (the “Offer to Purchase”), and in the related Letter of Transmittal (which, together with any amendments or supplements thereto, collectively constitute the “Offer”).

The information set forth in the Offer to Purchase, including all schedules thereto, and the related Letter of Transmittal is expressly incorporated herein by reference with respect to all of the items of this Schedule TO, except as otherwise set forth below.

All capitalized terms used in this Amendment No. 22 without definition have the meanings ascribed to them in the Schedule TO.

Item 10.  Financial Statements.

Not applicable.

Item 11.  Additional Information.

On February 19, 2008, Parent issued a press release announcing the completion of the Offer.  The subsequent offering period expired at 7:00 p.m., New York City time, on Friday, February 15, 2008.  According to Citibank, N.A., the depositary for the Offer, as of 7:00 p.m., New York City time, on February 15, 2008, a total of approximately 34,545,323 Shares were validly tendered in the initial offering period and the subsequent offering period, representing approximately 93.7% of the outstanding Shares.  Purchaser has accepted for payment all Shares that were validly tendered in the Offer and the consideration for all such Shares either has been paid or will promptly be paid.

The acquisition of the Company is expected to be completed, on or about February 19, 2008, upon effectiveness of the Merger under the short-form merger provisions of Delaware Law without prior notice to, or any action by, any other Company stockholder.  At the Effective Time, each outstanding share of the Company not owned by Parent and its subsidiaries (other than shares as to which appraisal rights are validly exercised) will be converted into the right to receive the same $89.50 in cash per Share, without interest, that was paid in the Offer.  Following the Merger, the Company’s common stock will cease to be traded on the NASDAQ Global Select Market and the Company will become an indirect wholly owned subsidiary of Parent.

The full text of the press release issued by Parent is filed as Exhibit (a)(5)(xxi) hereto and is incorporated herein by reference.

Item 12.  Exhibits.

Item 12 is hereby amended and supplemented with the following information:

Exhibit (a)(5)(xxi)  Press Release issued by Roche Holding Ltd, dated February 19, 2008

SIGNATURES

After due inquiry and to the best knowledge and belief of the undersigned, each of the undersigned certify that the information set forth in this statement is true, complete and correct.

Date: February 19, 2008

ROCKET ACQUISITION CORPORATION
By:	/s/ Beat Kraehenmann
	Name:	Beat Kraehenmann
	Title:	Secretary
ROCHE HOLDING LTD
By:	/s/ Bruno Maier
	Name:	Bruno Maier
	Title:	Authorized Signatory
By:	/s/ Beat Kraehenmann
	Name:	Beat Kraehenmann
	Title:	Authorized Signatory

EXHIBIT INDEX

Exhibit No.	Description
(a)(1)(i)	Offer to Purchase dated June 27, 2007*
(a)(1)(ii)	Letter of Transmittal*
(a)(1)(iii)	Notice of Guaranteed Delivery*
(a)(1)(iv)	Letter to Brokers, Dealers, Commercial Banks, Trust Companies and Other Nominees*
(a)(1)(v)	Letter to Clients for use by Brokers, Dealers, Commercial Banks, Trust Companies and Other Nominees*
(a)(1)(vi)	Guidelines for Certification of Taxpayer Identification Number on Substitute Form W-9*
(a)(1)(vii)	Summary Advertisement dated June 27, 2007*
(a)(1)(viii)	Amended and Restated Offer to Purchase dated January 25, 2008*
(a)(1)(ix)	Amended and Restated Letter of Transmittal*
(a)(1)(x)	Amended and Restated Notice of Guaranteed Delivery*
(a)(1)(xi)	Amended and Restated Letter to Brokers, Dealers, Commercial Banks, Trust Companies and Other Nominees*
(a)(1)(xii)	Amended and Restated Letter to Clients for use by Brokers, Dealers, Commercial Banks, Trust Companies and Other Nominees*
(a)(5)(i)	Press Release issued by Roche Holding Ltd, dated June 25, 2007*
(a)(5)(ii)	Complaint filed in the Court of Chancery of the State of Delaware in and for New Castle County on June 29, 2007*
(a)(5)(iii)	Complaint filed in the United States District Court for the District of Arizona on June 29, 2007*
(a)(5)(iv)	Press Release issued by Roche Holding Ltd, dated July 11, 2007*
(a)(5)(v)	Excerpt from an Investor Presentation by Roche Holding Ltd, dated July 19, 2007*
(a)(5)(vi)	Transcript of an Investor Presentation by Roche Holding Ltd, dated July 19, 2007*
(a)(5)(vii)	Press Release issued by Roche Holding Ltd, dated July 25, 2007*
(a)(5)(viii)	Press Release issued by Roche Holding Ltd, dated July 26, 2007*
(a)(5)(ix)	Press Release issued by Roche Holding Ltd, dated August 21, 2007*
(a)(5)(x)	Press Release issued by Roche Holding Ltd, dated August 22, 2007*
(a)(5)(xi)	Press Release issued by Roche Holding Ltd, dated September 19, 2007*
(a)(5)(xii)	Press Release issued by Roche Holding Ltd, dated October 29, 2007*
(a)(5)(xiii)	First Amended Complaint filed in the Court of Chancery of the State of Delaware in and for New Castle County on October 26, 2007*
(a)(5)(xiv)	Press Release issued by Roche Holding Ltd, dated November 13, 2007*
(a)(5)(xv)	Press Release issued by Roche Holding Ltd, dated December 5, 2007*
(a)(5)(xvi)	Press Release issued by Roche Holding Ltd, dated January 16, 2008*
(a)(5)(xvii)	Press Release issued by Roche Holding Ltd and Ventana Medical Systems, Inc., dated January 22, 2008*
(a)(5)(xviii)	Summary Advertisement dated January 22, 2008*
(a)(5)(xix)	Press Release issued by Roche Holding Ltd, dated January 31, 2008*
(a)(5)(xx)	Press Release issued by Roche Holding Ltd, dated February 8, 2008*
(a)(5)(xxi)	Press Release issued by Roche Holding Ltd, dated February 19, 2008
(b)	Not applicable
(c)	Not applicable
(d)(1)	Agreement and Plan of Merger dated as of January 21, 2008 among Ventana Medical Systems, Inc., Roche Holdings, Inc. and Rocket Acquisition Corporation.*
(d)(2)	Guarantee dated as of January 21, 2008 between Roche Holding Ltd and Ventana Medical Systems, Inc.*
(d)(3)	Stockholder Tender and Support Agreement dated as of January 21, 2008 among Thomas D. Brown, Rodney F. Dammeyer, Edward M. Giles, Christopher M. Gleeson, Thomas M. Grogan, M.D., Hany Massarany, Lawrence L. Mehren, Mark C. Miller, Mark D. Tucker, James R. Weersing and Roche Holdings, Inc.*
(f)	Not applicable
(g)	Not applicable
(h)	Not applicable

* Previously filed

EX-99.A.5.XXI

Exhibit (a)(5)(xxi)

Media Release

Basel, Switzerland, February 19, 2008

Roche Completes Tender Offer for Ventana Shares

Acquisition of Ventana to be Completed Today

Roche (SWX: ROG.VX; RO.S; OTCQX; RHHBY) and Ventana Medical Systems Inc. (NASDAQ: VMSI) today announced that Roche has completed the tender offer for the outstanding shares of Ventana.  As of the expiration of the subsequent offering period, Rocket Acquisition Corporation, a wholly-owned subsidiary of Roche, had purchased a total of approximately 34,545,323 shares of Ventana common stock, representing approximately 93.7% of Ventana’s outstanding shares.  All shares validly tendered in the offer have been accepted for payment, and the consideration for all such shares either has been paid or will promptly be paid.

Roche expects to complete the acquisition of Ventana today through a short-form merger, without a vote or meeting of Ventana’s shareholders.  In the merger, all of the shares of Ventana not owned by Roche and its subsidiaries (other than shares as to which appraisal rights are validly exercised) will be converted into the right to receive the same cash consideration that was paid in the tender offer.  Following the merger, Ventana’s common stock will cease to be traded on the NASDAQ Global Select Market.

“This is a truly exciting day for Roche.  Ventana broadens Roche’s diagnostic offerings and complements Roche’s strong existing position in in-vitro diagnostic systems.  Incorporating Ventana will enhance our position as the world’s leading personalized healthcare company,” commented Franz B. Humer, Chairman and CEO of Roche.  “We are happy to officially welcome Ventana’s employees to the Roche Group and will begin the integration of our businesses immediately.”

Greenhill & Co. and Citi are acting as financial advisors to Roche and Davis Polk &

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Wardwell is acting as legal counsel.

About Roche

Headquartered in Basel, Switzerland, Roche is one of the world’s leading research-focused healthcare groups in the fields of pharmaceuticals and diagnostics. As the world’s biggest biotech company and an innovator of products and services for the early detection, prevention, diagnosis and treatment of diseases, the Group contributes on a broad range of fronts to improving people’s health and quality of life. Roche is the world leader in in-vitro diagnostics and drugs for cancer and transplantation, and is a market leader in virology. It is also active in other major therapeutic areas such as autoimmune diseases, inflammatory and metabolic disorders and diseases of the central nervous system. In 2007 sales by the Pharmaceuticals Division totaled 36.8 billion Swiss francs, and the Diagnostics Division posted sales of 9.3 billion francs. Roche has R&D agreements and strategic alliances with numerous partners, including majority ownership interests in Genentech and Chugai, and invested over 8 billion Swiss francs in R&D in 2007. Worldwide, the Group employs about 79,000 people.

Roche’s Diagnostics Division offers a uniquely broad product portfolio and supplies a wide array of innovative testing products and services to researchers, physicians, patients, hospitals and laboratories world-wide.

Roche commenced operations in the U.S. over 100 years ago and these operations include research and development centers that conduct leading-edge work in advancing disease detection and treatment. Our diagnostics and pharmaceuticals businesses in the

U.S. employ more than 20,000 people and generate approximately $10 billion in sales (including Genentech), accounting for about 40% of the Roche Group's global annual revenues.

For further information, please visit www.roche.com.

All trademarks used or mentioned in this release are protected by law.

Further information

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- All documents on the offer to Ventana’s shareholders: www.roche.com/info070625

Contacts for Roche:

Roche Group Media Office

Phone: +41 61 688 8888 / e-mail: basel.mediaoffice@roche.com

- Daniel Piller (Head of Roche Group Media Office)

- Alexander Klauser

Brunswick Group (for U.S. media)

Phone: +1 212 333 3810

- Steve Lipin

- Nina Devlin

MacKenzie Partners (for U.S. investors)

Phone: +1 212 929 5500

-Larry Dennedy

-Bob Marese

CAUTIONARY STATEMENT REGARDING FORWARD-LOOKING STATEMENTS

THIS DOCUMENT CONTAINS CERTAIN FORWARD-LOOKING STATEMENTS. THESE FORWARD-LOOKING STATEMENTS MAY BE IDENTIFIED BY WORDS SUCH AS ‘BELIEVES’, ‘EXPECTS’, ‘ANTICIPATES’, ‘PROJECTS’, ‘INTENDS’, ‘SHOULD’, ‘SEEKS’, ‘ESTIMATES’, ‘FUTURE’ OR SIMILAR EXPRESSIONS OR BY DISCUSSION OF, AMONG OTHER THINGS, STRATEGY, GOALS, PLANS OR INTENTIONS. VARIOUS FACTORS MAY CAUSE ACTUAL RESULTS TO DIFFER MATERIALLY IN THE FUTURE FROM THOSE REFLECTED IN FORWARD-LOOKING STATEMENTS CONTAINED IN THIS DOCUMENT, AMONG OTHERS: (1) PRICING AND PRODUCT INITIATIVES OF COMPETITORS; (2) LEGISLATIVE AND REGULATORY DEVELOPMENTS AND ECONOMIC CONDITIONS; (3) DELAY OR INABILITY IN OBTAINING REGULATORY APPROVALS OR BRINGING

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PRODUCTS TO MARKET; (4) FLUCTUATIONS IN CURRENCY EXCHANGE RATES AND GENERAL FINANCIAL MARKET CONDITIONS; (5) UNCERTAINTIES IN THE DISCOVERY, DEVELOPMENT OR MARKETING OF NEW PRODUCTS OR NEW USES OF EXISTING PRODUCTS, INCLUDING WITHOUT LIMITATION NEGATIVE RESULTS OF CLINICAL TRIALS OR RESEARCH PROJECTS, UNEXPECTED SIDE-EFFECTS OF PIPELINE OR MARKETED PRODUCTS; (6) INCREASED GOVERNMENT PRICING PRESSURES; (7) INTERRUPTIONS IN PRODUCTION; (8) LOSS OF OR INABILITY TO OBTAIN ADEQUATE PROTECTION FOR INTELLECTUAL PROPERTY RIGHTS; (9) LITIGATION; (10) LOSS OF KEY EXECUTIVES OR OTHER EMPLOYEES; AND (11) ADVERSE PUBLICITY AND NEWS COVERAGE. THE STATEMENT REGARDING EARNINGS PER SHARE GROWTH IS NOT A PROFIT FORECAST AND SHOULD NOT BE INTERPRETED TO MEAN THAT ROCHE’S EARNINGS OR EARNINGS PER SHARE FOR ANY CURRENT OR FUTURE PERIOD WILL NECESSARILY MATCH OR EXCEED THE HISTORICAL PUBLISHED EARNINGS OR EARNINGS PER SHARE OF ROCHE.

ADDITIONAL INFORMATION AND WHERE TO FIND IT

THIS PRESS RELEASE IS FOR INFORMATIONAL PURPOSES ONLY AND DOES NOT CONSTITUTE AN OFFER TO PURCHASE OR A SOLICITATION OF AN OFFER TO SELL VENTANA’S COMMON STOCK. THE TENDER OFFER IS BEING MADE PURSUANT TO A TENDER OFFER STATEMENT ON SCHEDULE TO (INCLUDING THE OFFER TO PURCHASE, LETTER OF TRANSMITTAL AND OTHER RELATED TENDER OFFER MATERIALS) FILED BY ROCHE WITH THE SECURITIES AND EXCHANGE COMMISSION (THE “SEC”) ON JUNE 27, 2007. THESE MATERIALS, AS THEY MAY BE AMENDED FROM TIME TO TIME, CONTAIN IMPORTANT INFORMATION, INCLUDING THE TERMS AND CONDITIONS OF THE OFFER, THAT SHOULD BE READ CAREFULLY BEFORE ANY DECISION IS MADE WITH RESPECT TO THE TENDER OFFER. INVESTORS AND SHAREHOLDERS CAN OBTAIN A FREE COPY OF THESE MATERIALS AND OTHER DOCUMENTS FILED BY ROCHE

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WITH THE SEC AT THE WEBSITE MAINTAINED BY THE SEC AT WWW.SEC.GOV. THE TENDER OFFER MATERIALS MAY ALSO BE OBTAINED FOR FREE BY CONTACTING THE INFORMATION AGENT FOR THE TENDER OFFER, MACKENZIE PARTNERS AT (212) 929-5500 OR (800) 322-2885 (TOLL-FREE).

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